Mercury-arc rectifier



March 1, 1932. s g E s -r AL 1,848,067

MERCURY ARC RECTIFIER Filed Jan. 28, 1930 Y ATTORNEY Patented Mar.

* UNIT-ED Atrnnn s mvxnns nun MoRIrZ 033113 v AssIGNoRs' '10wns'rmenonsn ELECTRIC. ,Armu's miuEeoTnnmecolumnar j oonroRArxon orrnnnsymvanI -a' v U B iflTlrfl fir 'i I 'Appma'tiim r n/ 2s, 1930, seial No- 2 ,985, ran 'd'in Geiinani'mctobei-i13,1927;

Our invention relates to improvements "in,- mercury'r-arc reotifiers,and more particularly to large rectifiers of high capacity.

It; is well known the -a-rt thati-at-the oath-: l6 Ode of mercury-arc:reotifiersfiiteen'to twenty- ,times the quantity of mercury vaporis-idelveloped which is needed for carrying through the v electricprocesses. This excess of vapor is liable to haveian" adverse eifectupon tlhe, m disoharge in the rectifier 1i 1t. is not condensed in thecondensing equipment which is acon'stituentof alllargerectifiers. Thecooling devices known for this purpose are all based upon the principle1to-provide lcopoling 1 surztaceeinthe pathofvthe vaporzupon which thevlapor should precipitateitself in the form ofdrops." It is herebya'ssumedrthat the mercury "vapor would seek out suchesurfaces with:avidity and would forthwith condense I upon them. I V 1 1 O-urinvention is on theother'hand based upon the observationthat:themercuryjiaporascending from the cathode ofmercury-arc rectifiers whenthe voutput of the rectifier-s; 28 per unit ofyol-ume isconsiderably.increa'setl" assumes different qualities owing to the Leonacentra'tion or crowding together of the heat v closely/as possible;downptoiya Itoenableithem toioatch [the sup,

development into smaller spaces; the vapor no longer leaves the cathodechamber in. a '80 saturated stat-gas assumed uptonomlmtiina-s'uperheated state and when-dealing with such a superheatedInercury'vapor-theknown cooling arrangements fail altogetl1er-=5orareunable totuhill their obj eat in :a. satisfactory 85' manner; According.to our invention the vapor clevelopchatzthe eathodezof largehighcapacity rectirfiers is therefore rfirst brought to saturationtemperature and saturation.

pressure "and then only condensed.

a With thisrend in :VlGW We provlde in the rectifier sbesides the usualcooling surfaces servln'g tor the i'condensatlon of the: vapor furtherspecial'rcoollng surf-aces which first cool the superheated vapor; Thecooling. 7 5,145 equipment of the rectifiergaccording :to our' inventionthus consists of a precoolerarranged asclosely as possible to the-1cathode and which may have any per 'se known shape, l and acondensingchamber, likewise of known 359 shapaior instanceginto which thevapor-does noi'lon ger enter ill the superheated 1 l r d t t e vpreferablywv itho.ut b'eing obstructed in i any w y 'sreed w i may ammmup t mete-rs per second.

should exceed; the width" of the cathode. a f ;Above;these cooingsoylihclers14,15 xi; v

to v conclcnse. surfaces does tenements, I

howeyeri; 1;:

embodiment of our. invent on iss 1 .-Z

tnateCl-in the drawingafiixed tothfs speeilioalj v tion. Theexampleshowsalarge high capace ity rectifiersq pp d wi ha-pre poling mia condensing (device'in yertical seotion.,' r R ferr ng .1 he rai i sitl b is el il tet' r it fi 1 1 011 tainsjthe' fcusto bo t m an'fc'odliiig coils "tubes 1 oroel'z'et sha edcoolers; Through thesecoolin-geyl inder's', an' innr cylinder 4*ai1'd an outer :c'y li nde r'5, ascends i vertically the superheated mercury vapor developed at thecathode;

way. Such: an arrangement; offering as? little: as possible-resistancetothe: flow; oi the vapor; isnecessary; because, asiwvell known; theinner- 'cu'ry .Va-por escapes from; theoathode ,at-a o 200,

2 The; ,cooling nenibers shoiilr e1 uoru I p as completely as ;p sibleand, only give the necessary passage tnee for the arcvdi rectecl r rfrolngthercatl ed inwa d thef nod Pref? erably the width of the, coolingeyli-nders a. newpur-pose, viz. the tcoolingi-oif thesup m in whichthere are located larger cooling surf iaces, upon-whichthe saturatedvaporiis able 7 he designmof ,theseloooling tp c 5 fo part-20f. 911

inventiom; particularly in ,view oiilth: vflC-i;

'that .-cqn clens ng. apparatus 1n'- Iectrfiers is not the chambers inwhich the anodes are located.

In this way the anode chamber 7 is kept free from superheated mercuryvapor of excessively'high vapor pressure as well as of saturated vaporwhich might their con dense at wrong places.

Provisions are furthermore made to keep thecondensate formed in thecondensation chamber 6 away from the anode chamber. This may forinstance, be effected in known manner by making use of the specificgravity of the condensate and separating it from the vapor bymeans ofbafiies or deflector plates 8. I

Itis a further essential feature of'our invention that these bafileplates also sepa rate theanode chamber in a'drip-proof mannerfrom thecooling and-precooling chambers and the condensing chamber. I

In our improved cooling equipment in which there are provided twocooling'chambers, a precooling chamber which receives the superheatedmercury vapors emanating from the cathode and cools them as far as thesaturated vapor is condensed should be maintainedat a slightly highertemperature.

Vhenobserving the above described conditions it: has been found that inthe operation of a large high-capacity rectifier equipped with the newcooling device "no condensation is noticeable at the precoolinc surfacesbut that the vapor is precipitated'in the form of drops only in thecondensation chamber proper. In this way any interference by themercuryvapor with the discharge process taking place within the rectifier iseffectively prevented and the output of the rectifier'per unit ofvolumecan be increased considen ably. r I

It has also proved advantageous to effect the evacuation of therectifier between the precooling and the condensing chamber, by, forinstance, letting the evacuation pipe ,9 leading to the vacuum pump openinto the rectifier above the precooling device; I i It Will beunderstood that various changes and modifications in the structureof'our improved rectifier may bemade without detank, a cooling meansconstituting a con-" densing chamber at the top portion of said tank,the rectifier being of such. design and rating that the mercury vapordeveloped at therath'ode is normally superheated, and a .secondcooling.means constituting a precooling chamber in the center of the spacewithin the tankv fornormally cooling said superheated mercury vapor tosubstantially the saturation temperature and pressure before.

it reaches said condensing chamber, characterized by protective wallsfor separating the spacein which the anodes are located from theprecooling and condensing chambers, so that the superheated as well thesaturated mercury vapor is kept awayirom it.

2. A high-capacity mercury-arc rectifier comprising an evacuated tank, amercury cathode centrally located in the bottom there-. of, a pluralityof anodes; disposedflaround the central. portion of the space within thetank, a cooling .n1eans constituting a condensingchamber at the topportion of said tank, the rectifier being of suchdesign and rating thatthe mercury vapor developed at the cathode is. normally superheated, anda second cooling means constituting a precooling chamber in the centerofthe space within the tank for normally cooling said superheated mercuryvapor'to substantially the saturation temperature and pressure before itreaches said condensing chamber, char: acterized by anoutlet means foreffecting the evacuation of the rectifier-tank,- said meanscommunicating with therspace' inside of the tank at a place between theprecooling chamber and the condensing chamber.

A high-capacity mercury-arc rectifier comprising-an evacuated tank, amercury cathode centrally located in the bottom there of, a plurality ofanodes disposed around the central portion of the space within the tank,a cooling means constituting a condensing chamber at the top'portion ofsaid tank, the rectifier being of such design'and rating that themercury vapor developed. at the cathode is normally superheated, and asecond cooling means constituting a precooling chamber in the center ofthe space within the tank for normally cooling said'superheatedmercury'vapor to substantially'the saturation temperature andpressure'betore itreaches said condensing chamber, characteriZed by anunrestricted communicating passage, as wide as possible, between saidtwo chambers, the precooling and condensing chambers being maintained atdifierent temperatu res, and protective walls for separating the space1n which the anodes are located from the precooling andcondensing-chambers, so that the superheatedas Well as the saturatedmercury vapor is kept away from it.

4. A high-capacity mercur -arc rectifier comprisingran evacuated tan amercury cathode centrally located in the botton'rthereof, a plurality ofanodes disposed around the central portion of the space within the.tank, a cooling means constituting a condensing chamber at the topportion of sa d tank, the rectifier being of such design and rating thatthe mercury vapor developed at thecathode is normally superheated, and asecond cooling means constituting a precoolmg chamber in the center ofthe space within the tank for normally cooling said superheated mercuryvapor to substantially the saturation temperature and vpressure before{it reaches said condensing chamber, char as I acterized by anunrestricted communicating passage, as Wide as possible, between saidtwo chambers, the precooling and condensing chambers being maintained atdifierent-tem-g peratures, and an outlet means for effecting. theeyacuation of the rectifier-tank, said means communicatingavith the spaceinside of the tank at a place between the precooling :chamber and thecondensing chamber.

5. A high-capacity mercury-are rectifier comprising an evacuated tank, amercury cathode centrally located in the bottom thereof, a plurality ofanodes disposed; around the central portion of the space Withinthe tank,a cooling means constituting a oondensing chamber, at the top portionofsaid tank, the rectifier being of such design and rating that themercuryvapor developed at the cathode vis normally superheated and asecond cooling means constituting a precoolmg chamber-1n the center ofthe space W1th1n the tank for normally 7 coolmg sa1d superheated mercuryvapor to substantially the saturation temperature and pressure before itreaches said condensing chamber, characterized by an unrestrictedcommunicating passage, as Wide as possible, between said two chambers,the precooling and condensing chambers being maintained'at difierentitem-j peratures. protective Walls for se tiarating the space in whichthe anodes are located from the precooling and condensing chambers, sothat the superheated as Wellas the'saturated mercury vapor is'kept awayfrom it, and an outlet means for efiecting'the evacuation of therectifier-tank, said means communicating with the spaceinside of thetank at a place between the precooling chamber and the condensingchamber. i

'6. t evacuated metal-tank mercury-arc rectifier having a main tankportion having an opening in the center of its bottom, a plurahty ofanodes insulatedly suspended thereof the main tankportion, around thecentral tion, said annularbaflle sloping somewhat downw'ardly from saidcylindrical baflle and i being above the" bottoms of the anodes, and"cool ng'means for said mam tank portion, {said coollng' means. being sodisposed as to admit of a substantially unrestricted vapor flowup'through the cylindrical battle and out over the annular bafiie.

' 7. The inventionjas defined in claim 6, L

characterized by said cooling means com-' prising means fol-conducting acoolingmedium into: contact with said cylindrical bafiie; 1" i 8 Theinvention as defined in claim 6, characterized by said cooling meanscomprising means forlconducting a cooling medium into 'contactavith saidcylindrical baf-u,

fle and a second, smaller,- similarly cooled .cyhndrically disposedcooling member within said cylindrical baflle. Y,

'9. Theinvention' as defined in claim/6, characterized by said coolingmeans com- .prising 'a smaller, cylindricall-y disposed member withinsaid cylindrical b'aflie, and means for conducting a cooling medium intocontact with the walls of said smaller, cylindrically disposed member. jr V -10. An evacuated metal-tank mercury-aro rectifier having a maintank portion having an opening in the center of its bottom, a

plurality of anodes ins'ulatedly suspended therewithin aroundthe'centerportion, a liq ind-mercury cathode member insulatedly at}tached and hermetically sealed to the bottom opening therein. coolingmeans forsaidmain. tank portion, said cooling means comprising acyllndrically disposed cooler supported centrally Within the main tankportion and clearof 'both thetop and the bottom of the tanln' andclearof the anodes and the cathode, an annular bafile extending fromnear the top of said cylindrical'lydisposed cooler to. the 1vi'cinityfof the side alls of said main tank portion, said annularbafiie sloping somevvhat downwardly from said cylindrically disposedcooler and being above. the bottoms of the anodes, andanevacuating-pumping .means for the rectifier. a

I In testimony-whereof, We have hereunto subscribed our names thisfilstday of De-' cember, 1929. I p

f V ALFRED SIEMENS.

' MORITZ SCHENKEL.

